1. Field of Invention
The present invention relates to a liquid crystal display. More particularly, the present invention relates to a liquid crystal display with common voltage compensation.
2. Description of Related Art
FIG. 1 depicts a conventional pixel circuit of a liquid crystal display. Referring to FIG. 1, in the pixel circuit, a source terminal 116 of a thin film transistor 113 is electrically connected to a source line 101; a gate terminal 114 is electrically connected to a gate line 103; and a drain terminal 115 is electrically connected to a common electrode 107 through a storage capacitor 111 and a pixel electrode 109 connected in parallel. In the liquid crystal display, there is a parasitic capacitor 105 between the source line 101 and the common electrode 107 due to the inherent process factors of the array circuit of the display panel.
Under the effect of the above parasitic capacitor 105, when the display panel displays certain particular frames, the voltage on the common electrode (hereinafter “common voltage”) will change due to the coupling effect generated by the parasitic capacitor 105, thus resulting in uneven luminance when the display panel displays the particular frames. The particular frames can be a frame with a black block, a white block and other gray scale block. For example, when a white frame with a black block 201 as shown in FIG. 2 is displayed, the luminance of two side regions 202 and 203 of the black block 201 will not be the same as that of the region 204 or 205 owing to the coupling effect generated by the parasitic capacitor 105.
If the influence of the coupling effect generated by the parasitic capacitor in the display panel is to be alleviated, conventionally the process should be modified to reduce the parasitic capacitance, however, the modification of the process is likely to have an effect on other characteristics of the display panel, and the cost is relatively high.